Dual intake rotary vane expander technology: Experimental and theoretical assessment

Fatigati, Fabio; Bartolomeo, Marco Di; Cipollone, Roberto

doi:10.1016/j.enconman.2019.02.026

Cited by 33 publications

(44 citation statements)

References 27 publications

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“…Clearly, the solar energy collection efficiency in binary phase region η PTC,b can be estimated with Equation (1) because water temperature remains constant in this phase. Consequently, in the binary phase region, the necessary collector area A b can be calculated by Equation (5), in which _ m is the mass flow rate of water through the PTCs (for the proposed SE-based DSG solar system, and it also represents the mass flow rate of working fluid circulating in the SRC), and Δh b is the enthalpy increase of water in the binary phase region 7 :…”

Section: Solar Power Collector Efficiencymentioning

confidence: 99%

“…Among different types of volumetric machines, screw and scroll expanders entail higher costs with respect to rotary vane expanders, which are of simpler design. However, the latter present higher internal leakages (between stator and vane tips) and higher friction losses, which entail lower isentropic efficiencies and rotational speeds with respect to SEs, thus reducing the available power …”

Section: Introductionmentioning

confidence: 99%

“…However, the latter present higher internal leakages (between stator and vane tips) and higher friction losses, which entail lower isentropic efficiencies and rotational speeds with respect to SEs, thus reducing the available power. 5 SE technology, which has achieved a significant grade of maturity in the last decade, compared with dynamic expanders, offers several advantages; and its fields of application diverge significantly from those of steam turbines utilized in large-scale SEGSs. Indeed, SEs are power machines, which can be used to convert heat to mechanical energy with satisfactory efficiency (also while expanding liquid-vapor mixtures) and net power lower than a few MW, 6,7 whereas steam turbines are generally used in current DSG solar systems supplying higher power output but without accepting two-phase flows.…”

Section: Introductionmentioning

confidence: 99%

“…Taking all these aspects into account, SEs become a competitive choice for DSG solar systems with respect to both dynamic expanders and other types of volumetric machines. 5 In effect, SEs available on the worldwide market are efficiently utilized in thermoelectric power at several European sites, comprising Italy, Spain, and France, supplying net power between 50 and 500 kW. However, such volumetric machines are also installed for higher power outputs in multiple installations.…”

Section: Introductionmentioning

confidence: 99%

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Energy performance and numerical optimization of a screw expander–based solar thermal electricity system in a wide range of fluctuating operating conditions

2019

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Summary This paper provides fundamental principles to study the thermodynamic performance of a new screw expander–based solar thermal electricity plant. While steam turbines are generally used in direct steam generation solar systems without admitting fluid in two‐phase conditions, steam screw expanders, as volumetric machines, can convert thermal to mechanical energy also by expanding liquid‐steam mixtures without a decline in efficiency. In effect, steam turbines are not as competitive as screw expanders when the net power is smaller than 2 MW and for low‐grade heat sources. The solar electricity generation system proposed in this paper is based on the steam Rankine cycle: Water is used as both working fluid and storage, parabolic trough collectors are used as a thermal source, and screw expanders are used as power machines. Since screw expanders can operate at off‐design working conditions in several situations when installed in direct steam generation solar plants, studying expander performance under fluctuating working situations is a crucial issue. The main aim of the present paper is to establish a thermodynamic model to study the energetic benefits of the proposed power system when off‐design operating conditions and variable solar radiation occur. This entails, first and foremost, developing overexpansion and underexpansion numerical models to describe the polytropic expansion phase, which considers all the losses affecting performance of the screw expander under real operating conditions. To assess the best operating conditions and maximum efficiency of the whole power system at part‐load working conditions under fluctuating solar radiations, parametric optimization is then improved in a wide range of variable working conditions, assuming condensation pressures of water increasing from 0.1 to 1 bar, under an evaporation temperature rising from 170°C to 300°C.

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Section: Solar Power Collector Efficiencymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Energy performance and numerical optimization of a screw expander–based solar thermal electricity system in a wide range of fluctuating operating conditions

2019

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“…In addition, screw expanders are typically suitable for low-grade heat recovery applications compared to other volumetric power machines [10,11]. Considering all these features, screw expanders are a realistic opportunity for DSG power plants in comparison with steam turbines and other sorts of volumetric power machines [5].That said, little is known about the exergetic assessment of screw expander-based solar thermal electricity plants at part-load operating conditions: The built-in pressure ratios of screw expanders are often much lower than the real expansion ratios in the case of actual solar systems with direct steam generation. Consequently, under these working conditions and adopting a single screw expander, the accessible enthalpy of expansion of high-temperature dry steam cannot be totally exploited [12,13].…”

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confidence: 99%

Exergetic Analysis of a New Direct Steam Generation Solar Plant Using Screw Expanders

2020

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Screw expanders are volumetric machines particularly suitable in energy conversion with steam–liquid mixtures and for the exploitation of low temperature heat sources. This study explored the main criteria to evaluate the thermodynamic advantages and exergetic assessment of an innovative solar electricity generation system: Screw expanders are utilized as power machines and parabolic trough collectors as a thermal source. Such a direct steam generation solar system, which is based on the Rankine cycle, offers benefits in comparison with usual power plants with dynamic expanders: The best exploitation of low temperature heat sources, satisfactory thermal efficiency with steam–liquid mixtures, lower evaporation pressures, and reduced size. Under real working conditions, screw expanders can work at part-load operating conditions; thus, the chief purpose of the present paper was to analyze the exergetic advantages of the planned solar power system when solar radiation and off-design working conditions fluctuate. Initially, the polytropic expansion phase with a specific numerical model is described to evaluate the energy losses that affect the thermodynamic performance of screw expanders when installed in the planned renewable energy power plant. Subsequently, to explore the exergy harnessing in the exhausted steam at off-design working conditions and then to appraise the maximum exergetic efficiency of the proposed screw expander-based solar thermal electricity plant, numerical optimization was performed in a broad range of evaporation and condensation temperatures.

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Combined use of volumetric expanders and Scheffler receivers to improve the efficiency of a novel direct steam solar power plant

Iodice

Amoresano

Langella

et al. 2021

Intl J of Energy Research

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This research proposes an innovative solar thermal plant able to generate mechanical power through an optimized system of heliostats with Scheffler-type solar receivers coupled with screw-type steam expanders. Scheffler receivers appear to perform better than parabolic trough collectors due to the high compactness of the focal receiver, which minimizes convective and radiative heat losses even at high vaporization temperatures. At the same time, steam screw expanders are volumetric machines that can be used to produce mechanical power with satisfactory efficiency also by admitting two-phase mixtures and with further advantages compared to steam turbines: low working fluid velocities, low operating pressures, and avoidance of overheating. This study establishes a mathematical model to assess the energetic advantages of the planned solar thermal power system by evaluating the solar-to-electricity efficiency for different off-

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Dual intake rotary vane expander technology: Experimental and theoretical assessment

Cited by 33 publications

References 27 publications

Energy performance and numerical optimization of a screw expander–based solar thermal electricity system in a wide range of fluctuating operating conditions

Energy performance and numerical optimization of a screw expander–based solar thermal electricity system in a wide range of fluctuating operating conditions

Exergetic Analysis of a New Direct Steam Generation Solar Plant Using Screw Expanders

Combined use of volumetric expanders and Scheffler receivers to improve the efficiency of a novel direct steam solar power plant

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